Wall units, having generally vertical passages therein defined by a plurality of horizontal rows of construction material stacked one atop another, are known. While these types of units can be employed in many different applications, they are especially useful when employed as integral components to heat transfer devices.
When used as parts of heat transfer devices, the wall units are often designed such that the passages defined therein open through at least the unit's bottom and/or top end.
One, but by no means the only, example of a heat transfer device wherein these types of wall units can be employed is a furnace, in which at least two independent wall units are generally spaced apart from one another to define a chamber therebetween. It is within this chamber that an item to be heated will be placed. Heated fluids and/or vapors are then channeled through the passages within each of the wall units. This increases the temperature within the chamber.
Industry has employed such wall units as a heat exchanger in many different ways. The overall heights of wall units employed in industry are dependent, in part, on their desired function, and can range from about three feet up to and exceeding forty feet.
One, but by no means the only, way in which such wall units are used, is in heating chambers for carbon baking furnaces. When constructing industrial-sized heat exchangers, it is often desirable, and/or more efficient, to prefabricate the wall units at a prefabrication site and then transport the prefabricated wall to a storage facility or directly to the installation site.
While wall units without openings through their bottom ends have been successfully prefabricated, problems result when prefabricating units which have openings passing through their bottoms. For example, one problem results when such a prefabricated wall unit is lifted using conventional lifting techniques.
A conventional technique of lifting and transporting wall units without openings through their bottom ends generally consists of placing a lifting means (e.g., a pallet) on top of the completed wall. Thereafter, generally vertical banding means are fitted around the periphery of the wall and over at least a portion of the lifting means to secure the lifting means to the completed unit.
The banding process employed in conventional lifting techniques generally consists of passing a vertically-oriented banding means under at least a portion of the wall unit's lowest course of construction material and over at least a portion of the lifting means. This conventional lifting process does not need a base pallet below the lowest course of construction material.
After the lifting means is securely attached to the prefabricated wall unit with the banding means, the structure is lifted by exerting an upward force on the lifting means. Since there is no base pallet employed with this conventional lifting technique, the structure can be lowered directly onto its installation site.
This conventional lifting technique cannot, however, be employed on prefabricated wall units wherein the passages therein open through the units' bottom end. If conventional lifting techniques are attempted, the sides of the wall will collapse into the passage, because when an upward force is exerted on the lifting means, the banding means exerts an inward force on the wall's lowest course of construction material. Since this course has the wall units' passages opening therethrough, the lowest course will collapse into these passages and all the remaining courses will follow.
Because of these problems, while it would be desirable to prefabricate industrial-sized wall units having generally vertical passages therein which open through the units' bottom, such walls are generally constructed on the installation site.
Moreover, even though it is known to prefabricate, lift and transport industrial-sized wall units wherein the passages therein do not pass through their bottom ends, problems can still arise in their prefabrication. While the prefabrication of such solid-bottomed wall unit's can be employed when constructing walls which are less than about ten feet tall, significant problems occur when constructing prefabricated walls which exceed this height. Specifically, when attempting to transport a prefabricated wall which is taller than about ten feet, problems result due to the relative clearance heights associated with overhead telephone and electric lines, bridges, tunnels and/or door openings.
While it may seem that this problem can be resolved by prefabricating the wall unit in a number of shorter sections, careful analysis indicates that this is not a solution. For example, if the prefabrication of a fourteen foot wall unit, having a passage therein which does not pass through the wall's bottom end, consists of prefabricating a lower and an upper section, the lower section can be successfully prefabricated, lifted, and transported using the aforementioned conventional lifting technique.
However, when prefabricating the upper section, the same problems will be encountered as those which result when employing the conventional lifting technique to lift an opened-bottomed wall unit. Specifically, while the wall may have a solid bottom, if the wall is bisected into two sections, the passage therein will also necessarily be bisected. Therefore, sectioning the wall will result in the upper section having an opening through its bottom end. As stated earlier, there is no known method for lifting such a prefabricated wall section without having it collapse in on itself.